I was reading about an idea that came into being in the late 19th to early 20th centuries about building canals from the Qattara Depression in Egypt to the Mediterranean Sea, especially creating a sea. Of course a lot of it was speculatory and mostly abandoned.
However, would there be any major human-related or ecological benefits in building bodies of water in the Sahara? If you were to create a Qattara Sea or fill depressions in North Africa in water by connecting them to the Altantic Ocean or the Mediterranean Sea?